This is one of my favorites. Japanese leaded enamel is torch
fired to a sugar texture. The rust color is just that, rust on copper. No
copper will not rust but a coating of iron fillings painted on copper will.
The close up shows you some marvelous things torch fire does to the leaded
enamel. The mirror finish is when the lead comes to the surface with heat.
The black triangle is black glass found on a beach in San Francisco then
tumbled in abrasive.